What is the easiest way to remove rust from a corroded venturi unit connected to the water-supply system?
First, let’s explain how a venturi unit works. It’s a conical-shaped metal or, more often, plastic piece with a nozzle at the smaller end, hidden inside the injector. When water travels through the nozzle, it increases in speed; then, when it hits the venturi, it is slowed down, which creates pressure.
A corroded venturi isn’t a big deal. Because they sit in water, venturis are almost always corroded. The problem is likely that the nozzle at the small end is clogged. You could try using a coat hanger to clean it out, but that won’t prevent more gunk from coming through. What you really need to do is disassemble the injector itself to get at the nozzle. If you have any difficulty getting the pipe fittings to come off, soak the whole unit in CLR. (Just be sure to give it a good rinse before reusing.) Once you get at the nozzle, it should unthread easily and can be cleaned out. If your nozzle is metal, you could also use a propane torch to heat the fittings until they come loose. And if all that seems like too much trouble and everyone is clamouring for water, you can buy a whole new injector unit. (Keep working on the old one when you have time, and hold on to it as a spare.)